In certain engine configurations, particular direct injection engines, fuel may accumulate in engine oil in a crankcase of the engine, for example during engine cold start and warm-up conditions, by impinging along the cylinder bore walls and flowing to the crankcase oil sump. The accumulated fuel may then evaporate out of the oil and into the crankcase while the engine is warming up and when the engine oil reaches a steady-state operating temperature. The crankcase vapors may be passed to the engine during crankcase purge. Fuel present in the oil and/or crankcase may affect various engine parameters and controls including fuel control and monitoring, engine oil viscosity, and the intake oxygen sensor output. Excessive fuel in the oil may decrease engine durability.
Attempts to address the above identified issues have included adjusting engine operation based on a fuel concentration in engine oil. However, the inventors herein have recognized an issue with the above approach. Such approaches typically assume that the fuel present in the oil is of similar composition as the fuel injected to the engine. However, the hydrocarbon species that accumulate in the oil and that evaporate into the crankcase may differ from the injected fuel, and the inventors herein have further recognized that these various species may differentially impact intake oxygen sensor output, for example.
Accordingly, an apparatus is provided to identify various hydrocarbon species present in an engine fluid. In one example, an apparatus comprises an analyzer to analyze an engine fluid and a computing device operably coupled to the analyzer, the computing device storing non-transitory instructions executable to determine fuel dilution in engine oil based on speciation of hydrocarbons in fuel in the engine oil determined based on output received from the analyzer.
In one example, the analyzer may include a gas chromatographer mass spectrometer (GC-MS) configured to output information usable by the computing device to identify each hydrocarbon species, and the concentration of each species, present in sampled engine oil. For example, the GC-MS may output a GC retention time for each of a plurality of engine oil fractions. Based on the retention times, as well as GC-MS data for a known set of hydrocarbon species, the hydrocarbon species present in the engine oil may be determined. Further, by determining various engine operating parameters at the time of sampling, such as engine oil temperature and crankcase pressure, the identity of various hydrocarbon species that have evaporated out of the engine oil and into the crankcase may be estimated. Based on identity and concentration of the hydrocarbon species in the crankcase and engine oil, more accurate engine fuel control, oil quality monitoring, and other parameters may be provided. Further, by identifying the hydrocarbon species present in the crankcase, an effect of the hydrocarbons on an oxygen sensor, such as an intake oxygen sensor, may be determined.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.